a) Field of the Invention
The present invention relates to a reversible thermosensitive recording material for forming an image and erasing the same by utilizing reversible transparency changes of a thermosensitive layer dependant upon temperature.
b) Description of the Prior Art
Japanese Laid-open Patent Application No. 154198/1980 (corresponding to Europian Laid-open Patent Application No. 14826) proposes a reversible thermosensitive recording material with a thermosensitive layer formed by dispersing an organic low molecular substance such as a higher fatty acid in a resin matrix such as a vinyl chloride type resin. The recording material of this sort forms an image and erases the same by utilizing reversible transparency changes of a thermosensitive layer. These recording materials are actually made transparent and opaque by heating. When in case the amount of said organic low molecular substance to said resin matrix is small, the opaque area (white area) of the recording material is low in concentration, while when the amount of the organic low molecular substance to the resin matrix is large, the opaque portion (white portion) is high in concentration but the transparency is low, whereby a sufficient contrast can never be obtained. Further, the temperature range between which the opaque portion is made transparent is narrow, namely about 2.degree.-4.degree. C. Due to this, when making the recording material, that is at least partly opaque, wholly transparent, or forming a colorless (transparent) image on a wholly opaque recording material, there can be observed such defects that temperature control is difficult and accordingly it is difficult to obtain a uniform transparent or opaque image.